Suppression of objectionable noise in rotating machinery



United States 3,080,014 SUPPRESSION OF OBJECTIONABLE NOISE IN ROTATINGMACHENERY Carl B. Dahl, Rockton, Ill., assignor to Beioit Iron Works,

l Beloit, Wis., a corporation of Wisconsin Filed Dec. 8, 1959. Ser. No.858,279 7 Claims. (Cl. 181-33) 'or surfaces which pass another membersuch as a mating roll, in close proximity thereto producingobjectionable noise. The iirst roll rotates at a given speed at or abovethe critical speed at which noise is generated, and hasits grooves atsubstantially uniform spacing generating noise inthe zone of proximityto the other member. The noisecommences at the critical speed andbecomes louder as the speed is increased. The grooves are normallyparallel to the axis of the roll. The present improvement positions thegrooves at a particular or critical angle so that the objectionablenoise is substantially eliminated. This angle is substantially equal tothe arctan of the speed of movement of the surface of the roll in feetper minute .divided by 33,600 or one half the speed of sound in feet perminute. The term arctan is used in the usual trigonometric senseindicating the angle whose tangent is the quantity set forth.

Accordingly, an object of the invention is to provide an improved rollstructure with grooves in the surface wherein noise generated by thegrooves passing in contact or momentary proximity to another member willbe substantially eliminated by positioning the grooves at an angle sothat each sound wave train originating at the impact or near impact ofthe groove with thev other member generates a wave train which isdisplaced by one half wave length or less from the wave train generatedby the adjacent groove.

'i Another object of the invention is to provide an improved groovedroll construction for use in machines such as paper Winders with thegrooves critically arranged to substantially eliminate objectionablenoise generated by the grooves.

"Other objects and advantages will become more apparent with theteaching of the principles of the invention in connection with thedisclosure of the preferred embodiments in the speciiication, claimsandfdrawings, in which:

FIGURE l is a fragmentary sectional view taken at right angles to theaxis of a grooved roll embodying the principles of the presentinvention;

' FIGURE 2 is a fragmentary plan view of the surface of the roll showingthe arrangement of the grooves;

' FIGURE 3 isa fragmentary sectional view showing a grooved rollrotating in close proximity to a iixed member; and

FIGURE 4 is a fragmentary elevational view illustrating the nip of twoadjacent rolls with one of the rolls having a herringbone grooveconfiguration thereon.

As shown on the drawings: i

As illustrated in FIGURES l and 2, a portion of a rotating rotor norroll 10 is shown having an outer surface 11v with grooves or recesses 12formed therein. The grooves are substantially equally spaced from eachother and the roll 1 0 rotates adjacent another member r13 such as aroll with a cylindrical outer surface 14. This arrangement brings thegrooves 12 into momentary proxim- The critical angle, as herein used, isdefined as thel g 16 with grooves 17 therein.

groove is in proximate relationship to the edge will be.

Y wave train originating in the impact or near impact .of the:

ity to the roll 13 and at rotational speeds above the critical speed ofthe roll 10, noise will be generated.

In accordance with the present invention the grooves are angled withrespect to the axis of the roll at a critical angle which causes thewave train generated between each groove and the roll 13 to be one halfa wave length or less away from the Wave train generated at the adjacentgroove. This obtains self-cancelling of the noise of each sound wavetrain originating in the impact or near impact of the groove with theadjacent member 13.

groove angle at which the noise of the roll is cancelled or eliminated.

FIGURE 3 illustrates another form of mechanism wherein a rotor or roll15 has a cylindrical outer surfacerotates past a fixed member 18 havingan edge 19 in close proximity to the roll surface 16 so that a soundwave train is generated as each groove passes the edge 19. Forconvenience of reference the zone wherein the referred to as theproximity zone.

The proximity zone is substantially at the' nip between the two rolls 10and 13 of FIGURE 1.

By making the rolls with the grooves set at an angle to the axis, andmaking or orienting the groove angle at a critical angle or at an anglegreater than this critical angle, so that the wave trains are one halfwave length or less apart, the noise generated is self-cancelling buttheloss of performance is zero or negligible. Where side thrust or reducedtraction, such as in paper rewinder respect to the roll axis and inaccordance with the present' principles the angle of the groove, or inother words, of?

the groove axis as indicated by the lines 21for the grooves 12, ismeasured with respect to the line 20 of the proximity" The angle 0indicates the angle of the grooves and' is positioned so that the angleis equal to the arctan of the speed of movement of the surface of theroll divided by one half the speed of sound. The grooves are angled -sothat sound wave trains from adjacent grooves, such as from the adjacentgrooves numbered 12 in FIGURE 2, are spaced substantially one half wavelength apart so that the sound wave trains originating from the grooves'at the proximity zone 20 will be self-cancelling. For example, if thespeed of surface of movement of the roll,

as may be indicated by the directional arrow 22, is measl'V ured in feetper minute, the arctan is obtained by vdividing by 33,600. v an anglewith respect to'the roll axis such that the laxial distance betweenadjacent grooves is equal to no more than one half a wave length of asound to be suppressed with the sound being the result of a givensurface'speed' of the roll with the grooves `spaced a given `distanceapart.

f In further illustration of the principle, the frequency of theprincipal objectionable noise,

f =g cycles/second where:

S=surface speed in feet per second a=peripheral spacing of recesses infeet.

To obtain self-cancelling of such noise each sound In this instance theroll' In some mechaf In other words the grooves extend at groovel orrecess fboundary, is associated with a substan-` tially equal wavelength train which is displaced by one half wave length or less. Thus byinclining the grooves which are normally parallel to the axis of theroll, lat a critical particular angle d, relative to the lineof'co-ntact where:

A-=the wave length vof the objectionable noise generated by a groovepassing an adjacent object. c=speed of sound.

=arctan of surface speed divided lby one half the speed of sound.

Thus for a roll or rotor which has a given surface speed?, the groovesmust be oriented at an angle which is at or greater than the criticalangle which is equal to the arctan of the surface speed in feet perminute divided by 33,600. The critical angle also may be ter-med asequal to the arctan of the surface speed divided by one half the speedof sound, preferably in the environment or location where the rotor isto be used, as of course is determined 4by the condition of surroundingatmosphere.

It will `be understood that while the angle used is preferablysubstantially at the critical angle or slightly greater so as to cancelnoise and yet not orient the groove at such a sharp angle as toadversely alfect the normal funci tion of the groove, angles greaterthan the critical angle may -be employed for noise cancellation.

The above principles are equally applicable to machines wherein themember in close proximity' to the roll is at an angle to the roll asaforementioned, and are applicable to other types of machinery and otherforms of paper machinery such as the Jordan type rener.

In paper machine winders of the type currently used the Winder speedsrequire angles, dependent on the predetermined speed, inthe range of9-13 As; illustrated in FIGURE 4, in some instances the side thrust orreduced traction may become .a problemv due to placing the grooves at anangle. In these instancesy the grooves may be reversed on the two halvesof the drum surface' to forml a chevron or herringbone pattern.Asillustrated in FIGUREv 4, a roll 23 meeting another roll 24 has thegrooves 2-5 on one half of the roll set at an angle with the angle ofthe grooves 26 on the other half of the roll.. The grooves are at anequal angle with respect to the roll axis. but meet in a V-joint.

The drawings and specification present a detailed disclosure of thepreferred embodiments of the invention, Iand it is to be understood thatthe invention is not limited to the specific for-ms disclosed, butcovers all modifications, chan-ges and alternative constructions andmethods falling within the scope of the principles taught by theinvention. f'

I claim as my invention: j

1. A sound suppressing means in rotating machinery comprising, a rotaryroll having equally spaced grooves in its surface, said groovesextending generally axially but at an angle with respect to the axis,said angle being such that the axial distance between adjacentgrooves isequal to one half a wave length of a sound to be suppressed, saidsoundbeing the result ofV r11-givenk surface speed of the roll with thegrooves spaced a given distance apart.

2. A sound suppressing means in rotating machinery in accordance withclaim l wherein said grooves are formed -by depressions in a cylindricalsurface.

3. A sound suppressing means in rotating machinery comprising, a rotaryroll having equally spaced grooves in its surface, said groovesextendi-ng generally axially but at an angle with respect to the axis,said angle being lsuch that the axial distance between adjacent groovesis equal to one half a wave length of a sound to be suppressed, saidsound being the result of a given surface -speed of the roll with thegrooves spaced a given distance apart, said angle being equal to thearctan of said surface speed in feet per minute divided by 33,6010.

Y4. A sound suppressing means in rotating machinery comprising, a rotaryroll having equally spaced grooves in its surface, said groovesextending generally axially but at an angle with respect to the axis,said angle being such that the axial distance between adjacent groovesis equal to one half a wave length of a sound to be suppressed, saidsound being the result of a given surface speed lof the roll with thegrooves spaced a given distance apart, said angle being equal to thearctan of said surface speed divided by one half the speed of sound. f

5.` A sound suppressing means yin rotating machinery comprising, arotary roll having equally spaced grooves in its surface, said groovesextending in a herringbone pattern to eliminate side thrust on the rollduri-ng rotation and extending generally axially but at an angle withrespect to the axis, .said angle being such that the axial distance'between adjacent grooves is equal to one half a wave length of a soundto be suppressed, said sound being the -result of a given surface speedof the roll with the grooves spaced a given distance apart.

6. A sound suppressing means in' rotating machinery comprising, a rotaryroll having equally spaced grooves Vin its surface, and a stationarysurface extending axially of the roll and being in close proximity tothe roll surface, said grooves extending generally axially but at anangle with respect to the roll axis, said angle being such that theaxialdistance between adjacent grooves is equal to one half a wavelength of a sound to be'suppressed, said sound being' the result of agiven surface speed of the roll With the grooves spaced a given distanceapart.A

7. A sound suppressing means in rotating machinery comprising, a rotaryroll having equally spaced grooves in its surface, said groovesextending` generally axially but at an anglel with respect to thel rollaxis, said angle being such that the axial distance between adjacentgrooves is no larger than one halfawave lengthof the sound to'besuppressed, said sound being the result of a given surface speed of theroll with the grooves spaced a given distance' apart. Y

References Cited in the tile of this patent UNITED STATES PATENTSV1,946,367 Straight Feb. 6, 1934 1,946,838v Coffin Feb. 13., 19341,996,418 Hargraves Apr. 2,1935 1,999,988 Anderson Apr. 30, 19352,110,471 Petruchkin Mar. 8, 1938v 2,179,579 Morral et al Nov. 14, 1939v2,245,109 Lapeyrouse June 10, 1941 2,453,240 Malmros Nov. 9, 19482,770,279 Harrison Nov. 13, 1956 2,893,487 Dahl et al. July 7, 1959FOREIGN PATENTS 801,497 Great Britain Sept. 7, 1958 OTHER REFERENCESC.W.E. Walker; The Poweu River ysuenen R011' Silencer, Noise Control,vol 2,V No. 5, September 1956, pages 39-45 and 58. 1

1. A SOUND SUPPRESSING MEANS IN ROTATING MACHINERY COMPRISING, A ROTARY ROLL HAVING EQUALLY SPACED GROOVES IN ITS SURFACE, SAID GROOVES EXTENDING GENERALLY AXIALLY BUT AT AN ANGLE WITH RESPECT TO THE AXIS, SAID ANGLE BEING SUCH THAT THE AXIAL DISTANCE BETWEEN ADJACENT GROOVES IS EQUAL TO ONE HALF A WAVE LENGTH OF A SOUND TO BE SUPPRESSED, SAID SOUND BEING THE RESULT OF A GIVEN SURFACE SPEED OF THE ROLL WITH THE GROOVES SPACED A GIVEN DISTANCE APART. 